Iona Island is located in the Town of Stony Point in Rockland
County, six miles south of West Point. From NYC go north on the Palisades Parkway about 40 miles
toward Bear Mountain Bridge. Take 9W south at the traffic circle, passing Bear Mountain Inn. Iona Marsh is 1 mile south of the Bear Mountain Bridge. Turn left and drive over the railroad tracks and park outside
the gate along the railroad.

Geology:

Iona Island is a mostly Precambrian gneiss bedrock island in
the midst of the Hudson Highlands, bordered to the west and the
southwest by Salisbury and Ring meadows, two large tidal marshes;
and the mouth of Doodletown Bight, an expanse of shallows and
mudflats. Doodletown Brook flows into the area.

"The Iona Island Delta, consisting mainly of mud
deposited by Doodletown Brook in recent time, occupies the
channel followed by the Hudson before the Pleistocene Epoch."
(Wyckoff 1971:78) Sediments are more than 100 feet thick.

The gneiss rock is very resistant to erosion and forms the
rocky knobs of Iona that project 100 feet above the river. (see
Hudson River NERR website)

Around the island is a 200 acre marsh on the former site of an ancient
horseshoe bend. The bend was bypassed with the last glacier that came through
the area and straightened out the river channel. (Binnewies, 2001:110-111)

Habitat:

In the 1970s, when there was abundant rainfall, the Hudson ran
full and strong, pushing the seawater downstream, so that the
river at Iona was only mildly brackish.

This is a brackish -- slightly salty -- river marsh. 50 miles
from the ocean, the Hudson is still tidal here. The salinity of
the marsh varies significantly, depending on the rainfall
upstream.

History:

A separate island, Round Island, was attached to the south end
of Iona Island with fill in the early 20th century. Iona Island
and its associated tidal wetlands have been designated a National
Natural Landmark by the National Park Service.

Native Americans occupied the island as much as 5,500 years
ago. Archaeological sites have been scientifically excavated and
documented on Iona Island with some of the artifacts on display
at the Bear Mountain Trailside Museum and Zoo.

Whites settled on the island in 1683.

1849 -- John Beveridge becomes owner of the island. He sells part-interest in
the island to his son-in-law, Dr. C. W. Grant. His attempt to develop an "Iona"
variety of grape only resulted in a wine of mediocre taste and his business
failed. (Binnewies, 2001:111)

In the Mountain House era, Iona Island was a favorite retreat
for day visitors. It had a ferris wheel, carousel and picnic
grounds. It also had a resort hotel. (Dunwell 1991:92)

On the 1854 map what became Iona Island was made of two
northerly islands (known as Salisbury Island), while the
southerly island was known as Round Island.

On the 1859 map the most northerly island was known as Ionia
Island, the middle one known as Courtland Island, and the one in
the south east was labeled Dr. Grant.

At the time of the Civil War, Iona Island produced
commercially grown fruit. During the Civil War itself, the island
was converted to a resort hotel.

Later owners turned the island into a resort complete with picnic ground. The
famous Irish-American fighter, John L. Sullivan, world heavyweight boxing
champion, frequently visited the island. (Binnewies, 2001:111)

On the 1876 map there is a dotted line going across the three
islands with the designation "Proposed Chicago & West
Shore Railroad."

On the 1891, map there are 4 island-like areas: Iona Island,
Depot, unmarked, and another area known with the designation D. E.
Donellan.

In 1899, the Navy purchased Iona Island for $160,000 dollars for use as a munitions
depot through World War II. The US Navy thought the location of the island,
being 40 miles upriver from New York City, provided it protection from attack.
Just before US entry into World War I the US Navy established an ammunition
depot at Iona Island with enough explosives to supply both the US and British
fleets in the Atlantic. (Binnewies, 2001:98-99)

Its construction began around 1900.
This, as well as an aqueduct from Doodletown to supply water to
the island, provided jobs for the people living in the now
abandoned village of Doodletown. There was an explosion at the naval magazine and a man from
Doodletown died.

The 1920 maps shows Iona Island with the U.S. Naval Station
designation and the West Shore Railroad.

After 1945 the Navy gradually deactivated the Iona Island
munitions depot. Scores of decommissioned combat and merchant
vessels were mothballed and anchored in the Hudson River off
Jones Point. The government used the vessels for surplus grain
storage.

In 1965, the Palisades Interstate Park Commission (PIPC)
purchased the island for use as a recreation area and bird
sanctuary.

Exploration of the fresh water swamp on this island was not
attempted because of the excessive heat. Yet, on the swamp edge
and on the knoll, a number of interesting plants were seen, at
what the leader believes is their only station in the county.
They were Cheilanthes lanosa, Arisaema stewardsonii, Habenaria
clavellata, Zanthoxylum americanum, Ptelea trifoliata, Asclepias
verticillata, and Campanula rotundifolia forma albiflora.
Attendance: Torrey 8, Rockland Audubon, 6 Leader, J. Harry Lehr.

June 16, 1957.

One of the botanical features of this area is a single
specimen of Ptelea trifoliata (common hoptree), the only one
known in Rockland County. This field trip disclosed the tree all
but dead as the result of right-of-way spraying by the railroad
where this plant grew beside the tracks. Yet, this loss was
somewhat compensated by the discovery of a station on the island
for Arenaria stricta (rock sandwort), a rarity within the Torrey
range and a new addition to the flora of Rockland County.
Attendance, Torrey 5; Connecticut Botanical Society 1. Leader, J.
Harry Lehr.

June 5 1960

Although both Typha angustifolia and T glauca were far enough
advanced in bud for their difference to be noted, the station for
Arisaema stewardsonii was disappointing. Scores of plants were
observed yet none were or had been in bloom. Could an abnormally
high water table in the area in May have been responsible for
this total lack of bloom?

On the shore of the inlet at the north end of the island
Amorpha fruticosa was found in flower. Along the railroad tracks
which bisect the island, two additions were made to the list of
Rockland County plants which is a continuing study of the leader.
They were Agrostemma githago (corn cockle), a single specimen,
and Mirabilis nyctaginea (umbrellawort), a western plant rapidly
becoming naturalized in the east. But the railroad tracks also
produced a disappointment, for the single specimen of Ptelea
trifoliata reported from Rockland County is now a dead skeleton.
The leader first found this tree in 1953 and its history since
then has been one of yearly deterioration. The reason?
Indiscriminate right-of-way spraying by the railroad. Attendance
4. Leader J. Harry Lehr.

8/20/63. The island contains at least 40 species unknown
elsewhere in the county, and a number of rarities or plants at
the northernmost or southernmost known limits of their range in
New York State. Some of them are

Fragments of submerged flora washed along the edge of the
marsh included Ceratophyllum demursum, Myriophyllum spicatum,
Najas flexilis, Potamogeton crispus, and Vallisneria americana.

We found a few plants of Trapa natans which apparently is
reaching its downstream limit in the Hudson River. Lemna minor
and Spirodela polyrhiza were floating on the water surface. A
return trip at low tide should reveal additional species that
grow lower in the intertidal zone.